Electrocleaner composition and process

ABSTRACT

Electrolytic caustic cleaning compositions are improved by adding to the composition from 0.33 to 3.0 percent by weight of the dry cleaning composition a monophosphate ester of oxyalkylated alcohol. The phosphate ester improves the cleaning efficiency of the electrolytic process and at the same time, minimizes the formation of spray, mist and the discharge of gases from the bath.

United States Patent Otrhalek et al. May 16, 1972 [54] ELECTROCLEANER COMPOSITION 3,078,203 2/1963 LaBoda ..204 14s R AND PROCESS 3,207,683 9/1965 Hermann ..204/145 R 3,445,355 5/1969 Woodberry.. ..204/141 Inventors: J p Otrhalek, bearbomi Harold 3,468,774 9/1969 Kendall ..204/141 Skmner, Wyandotte, both of M1011 3,528,896 9/1970 Davidofi et al. ..204/141 [73] Assignee. iWyandotte Corporation, Wyandotte, Pr a y E m ne j hn H. Mack Assistant Examiner-T. Tufariello Filedi 1971 Attorney-Robert M. Phipps, Robert E. Dunn, Bernhard R. [21 AppL No; 113,752 Swick, Joseph D. Michaels and Arnold S. Weintraub [57] ABSTRACT [52] US. Cl. .204/141, 204/145 R 51 Int. Cl. ...C23b 1/00, C23b 1/04 caustc li are by [58] Field of Search I D 204/1 145 134/2 adding to the composition from 0.33 to 3.0 percent by weight of the dry cleaning composition a monophosphate ester of oxalk lated alcohol. The hos hate ester im roves the cleanin [56] References Clted Zfficlency of the electrglyti: process and at the same time UNITED STATES PATENTS minimizes the formation of spray, mist and the discharge of gases from the bath. 2,420,602 5/1947 Kmgerley ..204/145 R 2,915,444 12/1959 Meyer ..204/145 R 7 Claims, No Drawings ELECTROCLEANER COMPOSITION AND PROCESS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the prevention of mist spray and discharge of gases plus improving the efi'rciency of electrolytic cleaning baths by the use of a monophosphate ester of an oxyalkylated alcohol dissolved in aqueous caustic solutions employed in electrolytic cleaning baths.

2. Description of the Prior Art It is well known in both anodic and cathodic aqueous electrolytic cleaning processes to use ordinary surface-active agents to achieve a measure of mist and spray control which is caused by gases evolved by and liberated in aqueous electrolytic processes. However, as is often the case, the use of these ordinary surface-active agents in these products leave something to be desired in the way of efficiency and spray and mist control. Thus, it is an object of this invention to provide an improved electrolytic caustic cleaning composition. It is further an object of this invention to provide an improved electrolytic cleaning process. These and other objects will become more apparent upon reading of the following specification.

SUMMARY OF THE INVENTION In accordance with this invention there is provided an improved electrolytic caustic cleaning composition wherein the improvement comprises adding to the dry caustic composition from 0.33 to 3.0 percent by weight of the final dry caustic composition, a monophosphate ester of an oxyalkylated alcohol of the formula A-OR-H wherein A is an alkyl group having from to carbon atoms, R is a random mixture of oxyethylene and oxypropylene, said mixture being from 67 to 80 percent of the total weight of the compound and the weight ratio of oxyethylene to oxypropylene in said mixture being in the range from 3:1 to 7: 1. Electrolytic cleaning processes employing essentially insoluble anodes and cathodes with an aqueous caustic cleaning solution are improved by adding to the aqueous electrolyte from about 0.15 to 2.7 grams/liter of the foregoing phosphate ester.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Caustic cleaning compositions for use in electrolytic cleaning processes typically contain an alkaline material such as alkali metal hydroxide, alkali metal carbonates, alkali metal silicates and alkali metal phosphates as the principal source of alkalinity. The effect of the alkali may be accelerated by the use of organic materials such as sodium gluconate. Other modifiers are also added such as trisodium nitrilotriacetate or a sodium phosphate to improve the retention of the dirt in the solution. It will be recognized of course that some of the alkali metal salts such as soda ash also have a dirt suspending property. In these cleaning compositions, the alkali metal or caustic component is the major component and will normally constitute over 50 percent of the composition and more typically over 75 percent. To this composition is also added small amounts of an ordinary surface-active organic composition in an attempt to control spray and mist elimination plus reducing the dustiness of the dry alkali mix. However, most of these organic surface-active agents are subject to attack by the alkali upon prolonged standing resulting in the discoloration and decomposition of the organic surface-active composition.

It is now been found that one type of surface-active organic composition can be transformed into a very useful and highly effective additive for caustic electrocleaner compositions by converting the surface-active agent into a monophosphate ester. The oxyalkylated alcohols which are used to prepare the monoesterified phosphoric acid esters useful in this invention have the formula A-O-R-H wherein A is the residue of the starting alcohol, and R taken collectively represents the residues of the oxyethylene and the oxypropylene groups used to oxyalkylate the alcohol. A is an alkyl group having from 10 to 20 carbon atoms or a mixture of alkyl groups having predominantly, that is, at least about percent, from 10 to 20 carbon atoms. The alcohol employed or the mixture of alcohols employed should have an average molecular weight of about 160 to about 260. Furthermore, it is preferable that the bulk of the alcohol so employed would be within the range of 10 to 15 carbon atoms. As previously indicated, R represents the propylene oxide and ethylene oxide residues used in oxyalkylating the alcohol. This mixture of alkylene oxide residues is a random mixture as opposed to a block or regularly ordered sequence mixture. The mixture will contain a weight ratio of ethylene oxide to propylene oxide residues in the range from about 3:1 to about 7:1 and more desirably from about 5:1 to about 7:1. On a weight basis the R component of the oxyalkylated alcohol will be from about 67 percent to about 80 percent of the total weight of the oxyalkylated alcohol.

The alcohols and oxides used to prepare the foregoing oxyalkylated alcohol are the normal typical ones of commerce. Examples of alcohols which are useful include decyl alcohol, dodecyl alcohol, tetradecyl alcohol, cetyl alcohol, lauryl alcohol, stearyl alcohol and eicosyl alcohol. Branched chain aliphatic alcohols are not operable in this invention. Mixtures of the alcohols can also be used. Included in the foregoing are blends of alcohol commercially available under names such as ALFOL I218 which is approximately a mixture of 40 percent (by weight) C alcohol, 30 percent C alcohol, 20 percent C alcohol and 10 percent C alcohol, ALFOL 1210 which is approximately a mixture of 70 percent C and 30 percent C alcohols and NEODOL 25 mixture of C C alcohols.

The products of this invention are prepared by condensing an alcohol or a mixture of alcohols as described above with a mixture of ethylene oxide and propylene oxide. The oxide mixture may be added to the alcohol in one continuous step or it may be added in several steps. If the oxide mixture is added in several steps, it is not necessary that the amount of ethylene oxide and propylene oxide added in each step be within the required weight and ratio ranges. It is only necessary that the total amount of ethylene oxide and propylene oxide added constitute 67 to 80 weight percent of the condensate (surfactant) product and that the ratio of the total amount of ethylene oxide to the total amount of propylene oxide be in the range of about 3:1 to about 7:1. Thus, it is possible to add a first amount of oxide mixture which has more propylene oxide than ethylene oxide as long as subsequent amounts of oxide mixture added bring the total amount of the oxides added within the required ranges. It is also possible to add a first amount containing only propylene oxide and then to add additional amounts of the oxide mixtures. Again the only requirement is that the total amount of oxides added be within the critical ranges. The foregoing type of condensation is further elucidated in U.S. Pat. Nos. 2,677,700 and 3,444,242 which are incorporated herein by reference.

The oxyalkylated alcohols are generally prepared by condensing the alcohol with a mixture of ethylene oxide and propylene oxide in the presence of an alkaline catalyst. Catalysts which may be employed include sodium hydroxide, potassium hydroxide, sodium methylate, potassium acetate, sodium acetate and triethylamine. Any other types of catalysts commonly used for alkylene oxide condensation reactions can also be employed.

The condensation is preferably carried out at elevated temperatures and pressures such as C. to about C. and 30 to 90 psig. After the condensation reaction is completed, the catalyst is removed from the reaction mixture by any known procedure such as neutralization and filtration or ion exchange. It will be readily apparent to those skilled in preparing surfactants that many other combinations and permutations of pressures, catalyst and temperatures may be employed in the preparation of the oxyalkylated alcohols utilized in this invention and that such pennutations and combinations are to be considered within the scope of this invention.

Thereafter in substantially equal molar ratio, orthophosphoric acid is reacted with the oxyalkylated alcohol to obtain the phosphate esters of this invention. By the use of conventional esterification separation procedures any diester phosphates are removed from the monophosphate ester product.

The monophosphate ester of the oxyalkylated alcohol is preferably added to the dry caustic electrolytic cleaner composition in order to obtain the greatest benefits of this invention. As previously mentioned, the phosphate ester is stable in the presence of caustic and, therefore, does not discolor nor deteriorate. Additionally, the phosphate ester acts as a dedusting agent reducing or completely eliminating the fine alkali dust which is otherwise associated with such a dry mix. The order of incorporation of the phosphate ester into the dry electrolytic cleaner composition is not too important; however, the greatest benefits are achieved when all or most of the dry ingredients are first added to the blending tank and then the phosphate ester is added. Additionally, the phosphate esters can be added directly to the aqueous electrolytic cleaner bath composition but in so doing the subsidiary advantage of dust control is lost.

On the dry weight basis, the phosphate esters of this invention will comprise from about one-third of one percent to about three percent of the total dry caustic electrolytic cleaner composition. Best results are obtained when the electrolytic cleaner bath solution composition containing the phosphate ester has a concentration from about 40 to about 120 grams per liter of the composition of this invention. When the phosphate ester is added separately to the bath solution, satisfactory results are obtained by the addition of about 0. l to about 2.7 grams per liter of bath solution.

The examples below are included to illustrate the preparation and use of the compositions of the present invention but are not to be considered limiting. Unless otherwise specified, all parts are by weight and all temperatures are degrees Fahrenheit.

EXAMPLE I Anodic cleaning of steel, particularly for smut removal, wherein the following dry mix was added at a rate of 40 to I 20 grams per liter of cleaning bath:

Weight Percent Caustic soda 55.0

Sodium metasilicate, anhydrous 15.0

Sodium gluconate 8.0

Soda ash 2 l .0

Monophosphate ester of this invention Total: lO0.0

wherein the alcohol (a total of 22 parts) contained a mixture of approximately 40% t1, alcohol, 30% C alcohol, C alcohol and IOZ- C alcohol, and the alkylene oxide (78 parts) in a ratio of6.8:l ofethylene oxide to propylene oxide.

Temperature was 130 to 200 F. with a time of 10 seconds to 4 minutes and current density of 10 to 100 amps per square feet.

EXAMPLE II Cathodic and anodic cleaning of brass and anodic cleaning zinc die cast parts wherein the following composition was used:

wherein the'nlcohul (20 parts) was u mixture containing upproximutely 70 C alcohol and C alcohol, and ulltylenc oxide (80 parts) was it mixture of ethylene oxide and propylene oxide in the rutio of 3: l. The buth conditions were us in Example I.

EXAMPLE III Anodic cleaning of steel, particularly for oily types of soil, utilizing the following composition:

Weight Percent Caustic soda 50.0 Sodium metasilicate anhydrous 39.0 Sodium gluconate 1.0 Soda ash 9.5 The monophosphate ester of this invention 0.5

Total: l00.0

wherein the alcohol (20 pans) contained a mixture of C alcohol, 8.5% C alcohol and 6.5% C alcohol, and the alkylene oxide (80 parts) wherein the ratio ofethylene oxide to propylene oxide was 5.67:].

The composition was used at the rate of 60 grams per liter of cleaning bath solution at a temperature of F. The anodic current was supplied for a period of 15 to 30 seconds at an average current density of 10 amps per square feet. One inch of foam was obtained with soil removal (number 50 Iubricat ing oil from cold rolled steel panels) of 71 percent.

EXAMPLE IV (COMPARATIVE) Example III was repeated except that the phosphate ester was based on the oxyalkylated alcohol of 60 parts of the alcohol described in Example I and 40 parts of ethylene oxide: The foaming height was 1 inch and the percent soil removed was 43 percent.

EXAMPLE V (COMPARATIVE) EXAMPLE VI Under the conditions of Example I, a general purpose cleaning composition anodic for steel and zinc die cast and cathodic for nickel was prepared containing:

Weight Percent Caustic soda 25.0 Sodium metasilicate, anhydrous 40.0 Soda ash 3.3 Trisodium nitrilotriacetate monohydrate 3.0 Phosphate ester of Example II 0.7

Total: 100.0

The monophosphate esters employed in this invention produce a thicker or heavier and more uniform foam blanket thereby better controlling the amount of spray, mist and gases evolved from the cleaning solution, control the dustiness of the dry cleaning mixture without the composition or discoloration. More importantly, and completely unexpectedly, the phosphate esters have a cleaning efficiency (in the amount of soil removed and retained in the cleaning bath) of nearly twice other phosphate esters outside the scope of this invention.

The foregoing examples and methods have been described in the foregoing specifications for the purpose of illustration and not limitation. Many other modifications and ramifications will naturally suggest themselves to those skilled in the art based on this disclosure. These are intended to be comprehended as within the scope of this invention.

Having thus described the invention, what is desired to be claimed and secured by Letters Patent is:

1. An improved electrolytic caustic cleaning composition wherein the improvement comprises adding to the dry caustic composition from 0.33 to 3.0 percent by weight of the final dry caustic composition, a monophosphate ester of an oxyalkylated alcohol of the formula A-O-R-H wherein A is an alkyl group having from to carbon atoms, R is a random mixture of oxyethylene and oxypropylene, said mixture being from 67 to 80 percent of the total weight of the oxyalkylated alcohol and the weight ratio of oxyethylene to oxypropylene at said mixture being in the range from 3:1 to 7: l.

2. The composition of claim 1 wherein A has a molecular weight offrom 160 to 26.

3. The composition according to claim 2 wherein the ratio of oxyethylene to oxypropylene groups is from about 5:1 to 7:1.

4. A caustic electrolytic cleaning solution containing from about 40 to about grams of the composition of claim 1 per liter of cleaning solution.

5. In an electrolytic cleaning process employing essentially insoluble anodes and cathodes with an aqueous caustic cleaning solution, the improvement comprises minimizing the formation of spray, mist and discharge of gases, and improving the cleaning efficiency during the passage of an electric current by incorporating into said aqueous caustic cleaning solution 0.15 to 2.7 grams per liter of the phosphate ester of an oxyalkylated alcohol according to claim 1.

6. The process according to claim 5 wherein the alkyl A has a molecular weight of from to 260.

7. The process according to claim 6 wherein the weight ratio of oxyethylene to oxypropylene is in the range from about 5:1 to 7:1.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 5,665, 586 Dated My 16, 1972 Inventor(s) Josegh V. Otrhalek and Harold A. Skinner It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 12 after to, 26 should be --260--.

Signed and sealed this 5th day of December 1972.

(SEAL) Attest:

EDWARD M.FLI:;TCHER,JR. ROBERT GQTTSCHALK Commissioner of Patents Attesting Officer 

2. The composition of claim 1 wherein A has a molecular weight of from 160 to
 26. 3. The composition according to claim 2 wherein the ratio of oxyethylene to oxypropylene groups is from about 5:1 to 7:1.
 4. A caustic electrolytic cleaning solution containing from about 40 to about 120 grams of the composition of claim 1 per liter of cleaning solution.
 5. In an electrolytic cleaning process employing essentially insoluble anodes and cathodes with an aqueous caustic cleaning solution, the improvement comprises minimizing the formation of spray, mist and discharge of gases, and improving the cleaning efficiency during the passage of an electric current by incorporating into said aqueous caustic cleaning solution 0.15 to 2.7 grams per liter of the phosphate ester of an oxyalkylated alcohol according to claim
 1. 6. The process according to claim 5 wherein the alkyl A has a molecular weight of from 160 to
 260. 7. The process according to claim 6 wherein the weight ratio of oxyethylene to oxypropylene is in the range from about 5:1 to 7: 